Pipes are disposed in nuclear plants for conveying working fluids such as high-temperature and high-pressure fluids, high-temperature vapors, or cooling water. The pipes uses control valves to control the flow rate and pressure of conveying working fluids.
Please refer to FIG. 1A, which shows a cross-sectional view of the structure of a control valve 100. The control valve 100 comprises a valve base 110, a valve rod 120, and a driving unit 130. The valve base includes a cavity 112, which includes a communicating opening 111. The cavity 112 is used for connecting a plurality of pipes. The control valve shown in FIG. 1A can connect two pipes. A valve plug 121 is disposed at one end of the valve rod 120, which can be moved by the driving unit 130 and thus enabling the valve plug 121 to close or open the communication opening 111. As shown in FIG. 1A, the valve plug 121 closes the communication opening 111 and hence interrupts flowing of fluids between the two pipes. As shown in FIG. 1B, the valve plug 121 is away from the communicating opening 111 and thus opening the communicating opening 111. Then, fluids can flow between the two pipes. The location of the valve plug 121 relative to the communicating opening 111 can be adjusted according to the traveling distance of the valve rod 121. By controlling the openness of the communicating opening 111, the flow rate of working fluids can be controlled accordingly. The valve rod 120 includes an indicator 123. A scale 124 is disposed on the fixing frame located at the bottom of the housing 131. The scale 124 corresponds to the traveling distance of the indicator 123. Thereby, an observer can acquire the displacement of the valve rod 120 according to the reading of the indicator over the scale 124.
Components for nuclear plants must be examined and tested for determining if they comply with the regulations for nuclear-grade components. In addition to executing functions normally and safely under normal conditions, it should be guaranteed that the functions could be executed safety when external accidents or natural disasters happen. Specifically, the operations of control valves influence the conveyance of working fluids in the pipes of nuclear plants. They are not only related to the efficiency of power generation but also to the safety of nuclear plants. To elaborate, control valves need to operate normally when serious accidents, such as earthquakes or explosions, occur in nuclear plants. In addition, with equal importance, they should be able to operate normally after accidents. This is because the pipes may break after serious accidents. The control valves in various pipes must close or open correspondingly for controlling the working fluids to stop conveying or change directions of convevance.
Accordingly, before control valves are installed to nuclear plants, they must be examined and tested in an environment emulating accidents. Hence, whether the control valves comply with the quality and safety regulations for nuclear-grade components can be guaranteed.
In an examination and test system for control valve according to the prior art, high-temperature and high-pressure liquids are sprayed to a hermetic first chamber to form a transient high-temperature, high-pressure, and high-humidity environment inside the first chamber with a maximum pressure of 7˜10 kgw/cm2 and a maximum temperature of 200 degrees, and form a high-temperature and high-pressure environment with gradually decreasing temperature and pressure for emulating the environment inside a nuclear power plant when accidents, such as pipe breakage, explosion, or radiation leak, occur. The control valve is disposed inside the hermetic first chamber for enduring the high-temperature, high-pressure, and high-humidity transients. Then records and observations are performed for specific intervals at specific pressures and temperatures, to see if the control valve operates normally.
Nonetheless, in the high-temperature, high-pressure, and high-humidity transients, it is not possible for observers to enter the hermetic first chamber. They cannot observe and record the operational processes of the control valve promptly until the temperature, pressure, and humidity inside the hermetic first chamber decreases to the range where human bodies or equipment can endure.
Accordingly, the examination and test system for control valve according to the prior art has the drawback of inability in observing control valve promptly in high-temperature, high-pressure, and high-humidity transients. In addition, when an observer needs to observe and record, he needs to put on special apparels before entering the hermetic first chamber, which results in inconvenience in operations.